In the conventional process of manufacturing absorbent articles, such as disposable diapers, widely used is a method in which string-like elastic members (rubber) are arranged in portions to be processed into leg-surrounding regions and a crotch region which constitute an absorbent article so that the leg-surrounding regions and the crotch region should be more fitted to a person to wear the absorbent article (for example, a human body).
Specifically, in the manufacturing process, the string-like elastic members are placed in waveforms on a web with continua of components such as a back sheet and an absorption sheet to form absorbent articles. In other words, the string-like elastic members are placed in waveforms on the web conveyed by a crosswise conveyor system in which absorbent articles to be formed are arranged with a longitudinal direction of each of the absorbent articles going in a cross direction (a CD direction) which intersects a conveyance direction (an MD direction) of the web. In this way, the absorbent article having gathers to be fitted to the shapes of the leg-surrounding regions and the crotch region can be continuously formed.
As described above, as a method for placing string-like elastic members in waveforms on a web being conveyed, there is known a method in which a guide member guiding feeding positions of elastic members onto a web is driven by a cam (see Patent Literature 1, for example).
There is also known a method in which a guide member guiding feeding positions of elastic members onto a web is reciprocally moved in a cross direction intersecting a conveyance direction of the web (see Patent Literature 2, for example).
It is not realistic in terms of the layout of an apparatus to bring a guide member into contact with a nip point to align the nip point with the feeding position of a elastic member guided by the guide member. Here, the nip point is that at which an elastic member and a web are held between press rollers provided above and below the web and thereby come in contact with each other. For this reason, a certain distance is generally provided between the nip point and the feeding position. In other words, the distance has to be considered when the profile of a device moving the guide member is designed.
The inventors have discovered that, in the known technique, the aforementioned conventional apparatus for manufacturing an absorbent article has the following problem.
Specifically, to place an elastic member accurately in a desired position on a web being conveyed at high speed, the profile of a device such as a cam has to be elaborately designed in consideration of a distance between a nip point and a feeding position.
The present invention has been made in view of the foregoing circumstances. Accordingly, an object of the present invention is to provide an apparatus and a method of manufacturing an absorbent article that are capable of placing a elastic member in a desired position on a web being conveyed at high speed without elaborate profile designing.